This invention relates to intraocular lenses (IOLs) and in particular to IOLs that reduce or even eliminate irritation of the ciliary band or angle and the sulcus in the eye and reduce the incidence of pupillary block, and, if a natural crystalline lens is present, to reduce the risk of cataract formation.
IOLs are commonly used to modify vision. For example, IOLs are used to replace the natural lens of the eye when warranted by medical conditions. A common practice is to implant an IOL in a region of the eye known as the capsular bag or posterior bag or capsule. However, in this practice, a potential risk exists that cells from the eye may grow in front of and/or in back of the optical portion of the IOL. Such cell growth tends to block the optical portion of the IOL and impair vision.
IOLs may be implanted in regions of the eye other than in the capsular bag. Anterior chamber IOLs (AIOLs) and posterior chamber IOLs (PIOLs) are known in the prior art. These prior art IOLs are designed such that a portion of the haptics of the IOLs are located against the angle or ciliary band of the eye for the AIOLs or against the sulcus of the eye for the PIOLs.
A disadvantage of the prior art AIOLs is the risk that the fixation members or haptics of the AIOLs may irritate the ciliary band. A disadvantage of the PIOLs is the risk that the optic of the PIOLs may irritate the natural crystalline lens, if such lens is present, and possibly result in cataract formation.
Referring now to Prior Art FIG. 1, a posterior/anterior chamber intraocular lens (xe2x80x9cPACLxe2x80x9d) 10 combines the advantage of an optic 12 positioned in the anterior chamber 14 of an eye 16 and haptics 18 that position the lens resting in the sulcus 20. The PACL 10 reduces the opportunity of irritation to the angle or ciliary band 22 and the natural lens 24. Such PACLs are disclosed in U.S. patent application Ser. No. 09/166,328 filed Oct. 5, 1998, which is commonly assigned with the present application and is incorporated herein in its entirety by reference.
The eye 16 is comprised of a cornea 26 shown to the left and an iris 28 shown in the middle of the eye. It is to be understood that the cornea 26 is at the front of the eye 16. The iris 28 divides the eye 16 into the anterior chamber 14 at the front of the eye and the posterior chamber 30 in the back of the eye. The iris 28 also defines the pupil 32, which is the opening in the middle of the iris. In front of the iris 28 is the sclera spur 34. The sclera spur 34 and the iris 28 delimit the ciliary band 22. Behind the iris 28 is the ciliary process 36, from which extends the ciliary muscle 38. The ciliary muscle 38 supports the natural crystalline lens 24 of the eye 16. The iris 28 and the ciliary process 36 define the sulcus 20.
The haptics 18 of the PACL 10 are two opposing elongated fixation members that extend from the optic 12. The optic 12 defines an optical axis 50 that extends through the center 52 of the optic. The haptics 18 have a proximal segment 54 attached to the optic 12, an intermediate segment 56, and terminates in a distal segment 58. The optic 12 and the proximal segment 54 are located in the eye anterior chamber 14. The haptic distal segment 58 rests against the sulcus 20.
The intermediate segment 56 of the haptic 18 extends through a hole 60 in the periphery of the iris 28. The intermediate segment 56 is substantially parallel to the optical axis 50. The holes 60 may be formed by an iridectomy, or be naturally occurring openings in the iris 28. The holes 60 have an additional benefit of improving fluid flow between the anterior chamber 14 and the posterior chamber 30. Other details of the PACL 10 are disclosed in the above-incorporated U.S. Patent Application.
Recently developed AIOLs for insertion in eyes which contain the natural crystalline lens (xe2x80x9cphakicxe2x80x9d eyes) include the Nuvita(trademark) MA-20 lens, which has a four-point haptic for fixation in the angle, and is made of rigid polymethyl methacrylate (PMMA). Another AIOL used in phakic eyes is known as the Artisan(trademark) lens and is disclosed in Worst U.S. Pat. No. 5,192,319, which is incorporated in its entirety herein by reference. This AIOL is fixated on the iris by xe2x80x9cpinchingxe2x80x9d the iris tissue. Made of rigid PMMA, the Artisan(trademark) lens is difficult to implant due to the delicacy of the iris tissue. Worst U.S. Pat. No. 4,215,440, which is incorporated in its entirety herein by reference, discloses another iris-fixated AIOL, which uses one or more fixation members, each having a pair of pincer arms that pinch an anterior surface of the iris. This AIOL detachably attaches the IOL to the iris such that the optic is positioned in the iris opening and has many of the same disadvantages as does the Artisan(trademark) lens. Suzuki U.S. Pat. No. 5,628,796, which is incorporated in its entirety herein by reference, discloses an AIOL with fixation arms or support legs that are inserted in and through fine bores or apertures made by incision in a peripheral site of the iris.
Disadvantages associated with these IOLs for phakic implantation include a requirement for large incisions in the cornea for non-foldable IOLs and potential for damage and inflammation to delicate tissue from rigid haptics. Also involved are one or more of the complications which include corneal endothelial cell loss due to mechanical abrasion against the cornea, inflammation, pupil ovalization, problems with aqueous flow in the iridio-corneal angle, and implant decentration.
There continues to be a need for new IOLs.
New iris fixated intraocular lenses (IFIOLS) have been discovered. The present IFIOLs are relatively easy and straightforward to implant in the eye and effectively fixate to the iris of the eye. The present IFIOLs are adapted to be firmly fixated to the iris, for example, so as to prevent accidental dislodgement. These IFIOLs can be sized and structured so as not to interfere with the zonules and sulcus angle of the eye, and with the natural lens of the eye, if such natural lens is present.
The iris to which the present IFIOL is fixated has a side and a hole, for example, a iridectomy hole or opening, extending from the iris side and through the iris. In one broad aspect, the present IFIOLs comprise an optic and at least one fixation member or haptic. The fixation member is joined to the optic and includes a distal segment including a through-iris portion adapted to extend through the iris hole and an anchor portion. The anchor portion has or is adapted to have an anchor structure positioned to be disposed proximate to the iris side so as to be effective in fixating the IFIOL to the iris.
In one aspect of the invention, the optic is adapted to be disposed in the anterior chamber while the anchor portion is adapted to be disposed in the posterior chamber or the anterior chamber, preferably in the posterior chamber.
The anchor portion may have the anchor structure prior to the intraocular lens being placed in the eye or the anchor portion may be adapted to form the anchor structure after the intraocular lens is placed in the eye.
In one embodiment, the anchor portion adapted to form the anchor structure after insertion or placement in the eye may be comprised of hydrophilic material adapted to absorb aqueous fluid and form the anchor structure in the eye. The hydrophilic material used may be any suitable such material, for example, a material suitable for use in the eye. Examples of useful hydrophilic materials include, but are not limited to, acid-treated polymers, base-treated polymers, hydrogel-forming polymeric materials and the like and mixtures and combinations thereof.
In another embodiment of the invention, the anchor portion adapted to form the anchor structure after insertion in the eye may be comprised of an elastic memory material adapted to form the anchor structure in the eye. Any suitable elastic memory material may be employed, provided that such material is useful in the eye and can be treated in the eye to form the anchor structure at conditions which do not detrimentally affect the eye. Examples of useful elastic memory materials are well known in the art.
In one embodiment, the anchor structure has a transverse cross-sectional area that is larger than a transverse cross-sectional area of the through-iris portion of the fixation member. Also, the through-iris portion may, and preferably does, have a longitudinal axis oriented in a direction other than normal to an optical axis of the optic.
The IFIOLs of the invention may have at least three fixation members, for example, three or four fixation members, but may also have any number of such members. Further, not all of the fixation members need be adapted to fixate to the iris.
In one particularly useful embodiment, fixation member or members include a plate, or plate-like, element joined to the optic. Such plate elements have been found to effectively facilitate fixating the present IFIOLs to the iris. For example, the plate elements are effective in reducing, or even substantially eliminating, movement of the optic in the eye which can disadvantageously cause vision distortion. One important feature of these plate elements is in facilitating the placement of the IFIOLs in the eye. Thus, the relatively large and strong plate elements provide a degree of structural rigidity and are adapted to facilitate passing the distal segments of the fixation members into and through the holes in the iris. Such facilitation increases the ease with which the IOL is installed in the eye and, thereby advantageously, reduces patient trauma and/or surgeon stress.
In one aspect of the invention, the distal segment of the fixation member includes an other or an additional anchor portion having or adapted to have an other or an additional anchor structure. In this aspect, the first anchor portion is adapted to be disposed on one side of the iris, the second anchor portion preferably is adapted to be disposed on the other side of the iris, and the through-iris portion of the distal segment extends through the iris hole and between the two anchor portions. One or both of the two anchor structures may be formed prior to insertion of the IFIOL into the eye or may be formed after the IFIOL is placed in the eye. One of the anchor structures preferably is adapted to be disposed in the posterior chamber while the other anchor structure preferably is adapted to be disposed in the anterior chamber. In a very useful embodiment, the anchor structure is adapted to be formed after the IFIOL is placed in the eye and the other anchor structure is adapted to be present prior to the intraocular lens being placed in the eye. The two anchor structures may have substantially the same or different configurations.
In one embodiment, one or both of the anchor portion and the other anchor portion are adapted to enlarge in the eye and form an anchor structure, or comprise an elastic memory material adapted to form an anchor structure in the eye, or have a transverse cross-sectional area that is larger than a transverse cross-sectional area of the through-iris portion of the fixation member.
In one embodiment, the anchor structure adapted to be disposed in a posterior chamber of the eye has a generally elliptical transverse cross-sectional area. This is particularly useful when the anchor structure is formed prior to the IFIOL being placed in the eye. Such elliptical cross-sectional area facilitates placing the preformed anchor structure through the hole in the iris.
Methods of fixating an IOL, for example, the present IFIOLs, to an iris of an eye have been discovered. Such methods comprise inserting or placing the IOL into the eye, for example, through an incision in the eye. A distal segment of a fixation member of the IOL is directed through a through-hole extending through the iris such that a through-iris portion of the distal segment is disposed in the hole. The hole in the iris may be formed as part of the present methods, for example, employing conventional iridectomy techniques. An anchor structure of the distal segment is disposed or placed proximate to a side of the iris so that the anchor structure is adjacent the through-iris portion and the anchor structure is effective in fixating the intraocular lens to the iris.
In one embodiment, the anchor structure is a preformed anchor structure and the disposing step includes passing the preformed anchor structure through the through hole in the iris. Alternately, the present methods may include a step of changing the shape of an anchor portion of the distal segment in the eye to form the anchor structure. In this embodiment, the anchor portion may comprise a hydrophilic material and the changing step includes causing the anchor portion to absorb aqueous fluid, for example, from the eye, and form the anchor structure. The anchor portion may comprise an elastic memory material, and the changing step includes directing energy to the anchor portion, whereby the anchor portion absorbs the energy and the anchor structure is formed.
Each and every feature described herein, and each and every combination of two or more of such features is included with the scope of the present invention provided that the features included in such a combination are not mutually inconsistent.
These and other aspects of the present invention are apparent in the following detailed description and claims, particularly when considered in conjunction with the accompanying drawings in which like parts bear like reference numerals.